This invention relates to traffic safety equipment, and more particularly to an inertial barrier system for attenuating the energy of errant vehicles.
Inertial highway barriers have been used for some time to prevent vehicles from striking an obstacle such as a bridge pier or the like at full velocity. An inertial barrier relies on the mass of the barrier to decelerate the vehicle. Typically, a dispersible material such as sand is enclosed in a frangible container. When the vehicle strikes the container, the momentum of the impacting vehicle is dissipated in accelerating the sand.
In the current state of the art, standard arrays of sand-filled energy absorbing units are employed, with the amount of sand varying from one barrier unit to the next in a predetermined fashion so that an errant vehicle crashing into the barrier system is decelerated with minimum damage to the vehicle and its occupants. Because the plastic containers for these units are shatterable if struck at highway speeds, the effect of the barrier on stopping the errant vehicle comes about by transfer of momentum of the vehicle to the sand or other dispersible particulate medium. By arranging the barrier units, in order of striking, from lighter to heavier in terms of amount of sand contained therein, the errant vehicle can be caused to decelerate gradually and with minimum damage to the vehicle and minimum risk to its occupants.
Current standard arrays employ sand containers having weights of 200, 400, 700, 1400, and 2100 pounds. Customarily, spacers or lightweight supports are provided at the base of the barrel so that the center of gravity of the barrier unit is about the same as that of the errant vehicle, i.e. about two feet above the ground. This prevents the errant vehicle from either ramping or climbing over the units on collision or from nosing under the units. Presently, there are three primary methods for elevating the sand mass in a container. A first method, described in U.S. Pat. No. 3,606,258 to Fitch, utilizes a round Styrofoam pedestal or core at the bottom of a container. To obtain barrels having varying weights, the size of the core may be increased or reduced and/or the amount of sand used to fill the void in the barrel not occupied by the core may be varied. Alternatively, the Fitch ""258 patent discloses in FIGS. 12 and 13 an embodiment comprising a crushable base or pedestal section topped by a second section comprising a sand-fillable container. A second method, described in U.S. Pat. No. 4,289,419 to B. C. Young, employs an inverted U-shaped plastic support structure disposed at the bottom of the container. As shown particularly in FIG. 7 of that patent, the weight of the containers may be varied by using variously sized plastic support structures or cores to reduce or increase the interior volume of the container which is available for filling with sand.
Yet a third method, which is in primary use today, is described in U.S. Pat. No. 4,688,766 to Zucker. This method employs a plastic disc or core member 20 of a single size, which is supported on a flange disposed on the outer container. When a container having a weight of 200, 400, or 700 pounds is desired, the core is placed within the container in an upside-down configuration, as illustrated in FIGS. 2A-2C of the patent, and the proper amount of sand, according to provided markings, to achieve the desired weight, is introduced into the available reduced volume within the container. When a weight of 1400 pounds is desired, on the other hand, the orientation of the core is reversed, as illustrated in FIG. 3A of the patent, in order to increase the available volume of the container, which is filled with a greater amount of sand. Finally, when a weight of 2100 pounds is desired, as illustrated in FIG. 3B of the patent, the core is removed completely, and the container is completely filled with sand.
Each of the state-of-the art inertial barrier constructions has disadvantages. The system disclosed in the Fitch ""258 patent is disadvantageous in that Styrofoam pedestals or cores of differing sizes must be used for each desired weight configuration, and varying levels of sand must be utilized as well. This is labor intensive and relatively complex, involving the maintenance of an inventory of variously sized core elements. Furthermore, the containers all have identical external configurations, regardless of their weight, making ready identification difficult. As a result, external markings, using spray paint, for example, must be utilized to externally identify the weight of a particular container.
The system disclosed in the Young patent ""419 is similarly disadvantageous in that plastic support structures or cores of differing sizes must be used for each desired weight configuration, though at least the available volume in each container is filled in each instance, and there is no need to involve road crew personnel in partially filling containers to various levels. Again, the containers all have an identical appearance from the outside, making identification of the particular weight of a container difficult unless it is marked.
The Zucker patent ""766 is an improvement over both Fitch and Young, in that only a single sized core is employed for each of the desired weight configurations. However, the system is still disadvantageous in that the exterior appearance of the container is identical no matter what weight configuration is being employed. Additionally, because the sand mass within the container is elevated, in all but the 2100 pound embodiment, and the bottom of the container is tapered, having a smaller diameter than the top portion, the container is hard to move, because it is unstable. Furthermore, if such a container is utilized on uneven ground, the aforementioned tapering can cause bowing of the container wall.
What is needed, therefore, is an impact attenuator configuration having as few pieces as possible, wherein when the sand mass contained therein is elevated, the exterior sidewall of the attenuator container is at least as wide at its bottom portions as it is at its upper portions. Furthermore, it would be advantageous for such a system to be configured so that containers of varying weights have distinctive external appearances, so that the weight of a particular container may be readily discerned by inspecting its external configuration.
The present invention addresses the foregoing problems by providing an inertial barrier system comprised of inertial barriers formed of two modules, each of them being differently sized and being adapted to stack one upon the other. An interlocking geometry on each of the mating ends of modules assists in obtaining a secure stacking arrangement. One of the two modules functions as a container, facing upwardly so that its volumetric capacity is available for filling by a particulate ballasting material. The lower module functions only as a pedestal for the support of the upper module. The upper module is advantageously fillable to different predetermined levels, so that the apparatus, comprising the joined lower and upper modules, is capable of functioning as differently weighted barrier systems.
Other advantages of the invention include a system having a minimum number of individual parts, the elimination of a sand platform which can leak sand to lower portions of the barrier, and a large diameter base for the barrier in any configuration, in order to resist tipping of the barrier.
More particularly, there is provided an inertial barrier for protecting a vehicle from a roadway hazard, which comprises a container having an outer sidewall and an interior volume, and a mating end, and which further comprises a pedestal having an outer sidewall and a mating end. The pedestal of the combination is adapted to mate with and support the container in a vertical stacking orientation to together form said inertial barrier. Each of the pedestal and container mating ends includes a projecting portion, and the other of the pedestal and container mating ends includes a recess portion which is complementary to the projecting portion. Thus, when the container and the pedestal are joined together in the aforementioned vertical stacking orientation, the projecting portion is engaged into the recess portion to form an interlocking relationship between the container and the pedestal.
Preferably, the container further comprises an open end which communicates with the interior volume thereof, so that the container interior volume may be filled with a dispersible ballasting material, such as sand. Additionally, the container comprises a lip circumferentially disposed about the open end thereof, and the barrier further comprises a lid for covering the exposed open end of the container, with the lip engaging the lid to secure the lid in a closed position.
The pedestal preferably also comprises an open end, which comprises a base of the barrier. The barrier has an axial height, and the pedestal has a width at least equal to the width of the barrier at any other location along said axial height. In a preferred embodiment, the barrier, at an axial location where the mating ends of each of the container and the pedestal are joined, has a width smaller than the width at the barrier base.
In an advantageous feature of the invention, a portion of the outer sidewall of the pedestal forms an inwardly tapered conic section, in order to provide increased strength in compression for the barrier in the vicinity of the respective mating ends of each of the pedestal and the container, where the width (diameter) is smaller. This inwardly tapered conic section has been found to greatly improve the performance of the pedestal in supporting a filled container without collapsing at the narrower joint of the two mating ends, while still permitting an overall barrier construction having increased stability because of the wider base of the pedestal.
In another aspect of the invention, an inertial barrier for attenuating the energy of an errant vehicle is provided, which comprises a pedestal and a container disposed on the pedestal in a vertical stacking relationship to form a frangible barrier. Each of the container and the pedestal advantageously have an interlocking geometry at a joint therebetween, to prevent sidewards movement between the container and the pedestal, and to maximize performance of the barrier upon impact by a vehicle.
In still another aspect of the invention, there is provided a pedestal for use in an inertial barrier combination for attenuating the energy of an errant vehicle. The pedestal comprises an outer sidewall and a mating end which is adapted to mate with a container in a vertical stacking orientation to together form the inventive inertial barrier combination, wherein the pedestal supports the container. Advantageously, there is interlocking geometry disposed on the mating end of the pedestal, so that when the pedestal is joined with the container, the interlocking geometry engages complementary interlocking geometry on a mating end of the container to secure the pedestal and the container together.
In yet another aspect of the invention, there is provided a container for use in an inertial barrier combination for attenuating the energy of an errant vehicle. The container comprises an outer sidewall and a mating end, wherein the mating end is adapted to mate with a pedestal in a vertical stacking orientation to together form the inventive inertial barrier combination, with the pedestal supporting the container. Advantageously, there is interlocking geometry disposed on the mating end of the container, so that when the pedestal is joined with the container, the interlocking geometry engages complementary interlocking geometry on a mating end of the pedestal to secure the pedestal and the container together.
In another aspect of the invention, there is provided an inertial barrier system for protecting vehicles from a roadway hazard. This inventive system comprises a plurality of inertial barrier units arranged in a predetermined array, wherein at least one of the inertial barrier units comprises a container having an outer sidewall, an interior volume, and a mating end, as well as a pedestal having an outer sidewall and a mating end. The pedestal is adapted to mate with and support the container in a vertical stacking orientation to together form the inertial barrier unit. Advantageously, one of the pedestal and container mating ends includes a projecting portion, and the other of the pedestal and container mating ends includes a recess portion which is complementary to the projecting portion, so that when the container and the pedestal are joined together in the aforementioned vertical stacking orientation, the projecting portion is engaged into the recess portion to form an interlocking relationship between the container and the pedestal.
Preferably, in the inventive system, a plurality of the inertial barrier units comprise the two-piece type described above, having both a container and a pedestal. The containers of these multi-piece inertial barrier units are filled to varying levels with a dispersible ballasting material, resulting in inertial barrier units of varying weights, in a predetermined arrangement.
The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawing.